Motor operated screw jack



April 1966 YUKIYA IIMURA 3,244,401

MOTOR OPERATED SCREW JACK Filed April 6, 1964 2 Sheets-Sheet 1 /7 /2 /2'/7' 4 9 e 1/ N 00%10 0 JG IN VEN TOR.

April 5, 1966 I YUKIYA llMURA 3,244,401

MOTOR OPERATED SCREW JACK Filed April 6, 1964 2 Sheets-Sheet 2 mmvroza.YuKzlyw l llmww WWW United States Patent Ofiiice 3,244,491 Patented Apr.5, 1966 3,244,401 MOTGR GPERATED SCREW JACK Ynkiya limura, 61Miyata-cho, Hitachi, Japan Filed Apr. 6, 1964, Ser. No. 357,457 Claimspriority, application Japan, Apr. 2, 1963, 38/30,126 4 Claims. (Ci.254-103) The present invention relates to a motor jack provided with asmall electric motor.

A main object of the present invention is to provide a motor jackextremely small in size and light in weight and having a small motorthat can be operated from a lighter outlet on the dash panel of a motorcar, yet suitable for raising a motor vehicle.

Another object of the invention is to provide'a motor jack foolproof andeasy to handle, said motor jack being as small and light as possible.

Another object of the invention is a simple switch for changing thedirection of rotation of the jack motor.

A further object of the invention is a motor jack equipped with atransmission having a large reduction ratio, yet small in size.

Other objects of the invention will become apparent as the disclosureproceeds.

It is sometimes necessary to lift a car for repair. A hand operated jackis usually carried on a motor car for this purpose. A hook on the jackengages the body of the car. It requires a certain muscular strength tooperate such a manual jack. If the hook of the jack slips from the carbody an unskilled operator of the jack standing close to the car, asrequired, may be injured.

A portable jack of this kind is used only rarely, and the time of use isshort. The motor jack of the present invention employs a low-voltage andlow-ampere motor. It draws current through a plug on the lead wire ofthe motor which may be inserted into the lighter outlet on the dashpanel of the car. It can be operated even by an unskilled person who mayreverse the direction of the rotation of the motor by remote pushbuttons so that slipping of the jack hook from the car body cannot causean accident.

In the drawing:

FIG. 1 is a vertical sectional view of a first embodiment of theinvention;

FIG. 2 is a vertical sectional viewof a modified hook for the jack ofFIG. 1;

FIG. 3 shows the hook of FIG. 2 in section along the line A-A; 4 7

FIG. 4 shows another modified hook in vertical sectional view;

FIG. 5 shows the device of FIG. 4 in section along the line B-B;

FIG. 6 shows the jack of FIG. 1 in section along the line CC;

FIG. 7 shows the jack of FIG. 1 in section along the line DD; and

FIG. 8 is a diagram of the electric circuit of the moto jack.

In the motor jack shown in FIG. 1 an electric motor (12 volts DC, 80 w.)consisting of a rotor 1 and a stator 2 is arranged in a casing 3, saidstator 2 being fixed on the casing and said rotor 1 being fixed on theshaft 4 of the motor. The upper end of the shaft 4 is supported by meansof ball bearings 6 on the plastic end wall 5 on the upper end of saidcasing 3 and the lower end thereof is supported by means of ballbearings 8 on a supporting plate 7 on the lower end of said casing 3.

The electric motor used is of a low-voltage and lowampere type, itsfrequency of operation is comparatively low, its operating time isshort, and the switch mechanism which controls said motor for normal orreverse rotation has a construction adapted to this application. The center portions of two concentric, resilient, part-circular conductivestrips 11, 11 are fixed by screws 12, 12' on the internal surface of aswitch cover mounted on the end wall 5 of the motor by a screw 9. Pushbuttons 13, 13' are engageable with the resiliently movable free ends ofthe strips 11, 11'. The push buttons project through openings in saidswitch cover 10. Two lead wires 16, 16' pass through an opening 15equipped with a grommet 14 near the upper end of the casing 3 from themotor mechanism to a plug P shaped to be inserted into the lighteroutleton the dash panel of a motor car. The lead 16 makes contact with the setscrew 12 by means of a contact spring 17 which is fixedly attached tothe end wall 5 and is thereby connected to the conductive strip 11'. Theother lead wire 16 is connected to one terminal of the seriesconnectedfield coil of the stator 2. The other terminal of said field coil isconnected to a contact spring 17' fixed on the end wall 5 for contactwith the screw 12' and the strip 11. Fixed contacts 18, 18' and 19, 19'are arranged on the end wall 5 in alignment with the push buttons 13,13'. The contacts 19, 18 are connected by a wire a (FIG. 7) and thecontacts 18', 19 by wire b. The contacts 18, 18' are further connectedto the rotor 1 by carbon brushes 2%, 20' respectively.

The electric circuit is shown in FIG. 8. The push buttons 13, 13' arenormally held away from the contacts 18, 18', 19, 19' by the elasticityof the circular conductive strips 11, 11, and the circuit isinterrupted. When the push button 13 is depressed, the correspondingends of the strips 11, 11' touch the contacts 18, 19, and a circuit (asshown by an arrow) which connects the power source 16, 16' with thestator 2 is closed in such a manner that the motor rotates in onedirection for lift operation. When the push button 13 is released, theends of the strips 11, 11' are detached from the fixed contacts 18, 19by their resiliency and return to the initial position, therebyinterrupting the circuit. As will presently become apparent, the motorlifts a car by means of a pair of threadedly engaged members whosethreads have a small pitch so that the jack is self-locking under loadwhen the motor stops. When the push button 13 is depressed, the otherends of the strips 11, 11 are connected with the contacts 18', 19', areverse circuit is closed and the motor is rotated in the reversedirection for the removal of the jack from the load.

A reduction gear mechanism is driven by the shaft 4 of the electricmotor. As shown in FIG. 1, it includes a pin 21 movably fitted in thehollow lower end of the shaft 4. A pinion 22 is formed by teeth out intothe lower end of said shaft 4. A sleeve 26 is integral with a flange 24rotatably supporting two planet gears 23 which mesh with said pinion 22.Another pinion 25 is formed by teeth out into the sleeve 26 which isrotatably mounted on said pin 21. The lower end of the pin 21 isrotatably received in a hollow portion of a planet carrier 28 rotatablysupporting two planet gears 27 which mesh with said pinion 25. Theplanet carrier 28 is rotatably supported on a supporting plate 30 byball bearings 29 and is integral with an intermediate shaft 33 of whichthe lower end is fixedly mounted in a hollow screw 32 by a key 31. Theflange 24 planet carrier 28, and associated elements are enclosed in agear casing 35 whose internal surface is provided with internal ringgears 34. The planet gears 23, 27 simultaneously mesh with the internalgears 34 and the pinions 22, 25. The gear casing is provided on theoutside with a light source 37 including an electric lamp 36.

An outer tube 39 has axially spaced notches 38. Its upper end is fixedlyattached to the supporting plate 39.

A hollow cylinder 44 held in place by a resilient member 42 is slidablyreceived in the outer tube 39, and its lower end is releasably attachedto a foot 4% having a flat bottom plate The upper end 43 of the cylinder44 is internally threaded and threadedly engages the screw 32. The screwis provided on its upper end with a thrust bearing 48 which abutsagainst a supporting plate 49 fixed on the intermediate shaft 33.

The electric light 37 employs an ordinary low-voltage lamp 36 poweredfrom the lighter plug P in the same manner, not shown, as the motor. Thepermanently magnetic base plate 3'7 of the light source attaches thelamp to the side of the gear casing 35.

The hook 47 is slidably mounted on the outer tube 39 by a sleeve 50, anda bracket 51 projects from the other side of the sleeve. A pawl 4-6 isrotatably supported on the bracket by a pin 52, and a compression spring4-5 is so arranged on the rear end of the pawl 46 as to urge the tip ofthe pawl 46 into engagement with the notches 38.

Thus the motor jack of the invention is small and light enough to becarried in the car. In an emeregency, it is operated in the followingmanner: The plug P is inserted in the lighter socket. The hook 47 isadjusted by operating the push buttons 13, 13. The hook 47 is engagedwith a portion of the car such as the bumper, and the push button 13 isdepressed so that the motor rotates the intermediate shaft 33 and thescrew 32 attached to the shaft by the key 31, whereby the outer tube 39'together with the hook 47 move upward and are held in' the raisedposition by the pawl 46. When the push button l3 is pressed, and whenthe pawl 46 is disengaged, the motor rotates in the opposite direction,so that the hook 47 is lowered and may be removed from the body of thecar.

FIGS. 2 and 3 show a modified hook 47' integral with a sleeve Stiwhichis slidably mounted on the outer tube 39. The hook 47' is reinforced bytwo ribs 53 provided with bearing portions 54. An. eccentric disc isrotatably mounted in the bearings 54 by a pin 58. The eccentric disc 57has a handle 56 and a concave surface 55 which conforms to the outertube 39. FIGS. 4' and show another hook 47 integral with a sleeve 50.The hook is reinforced by two ribs 53' provided with hearing portions54' near the sleeve 50. A pin 58' is supported in the bearings 54' andpivotally carries a detent 46' having an arm 59 on which a weight 6% isatt'achedto urge the detent or pawl 46' into engagement with'the tube3%.

What is claimed is:

1. A motor jack comprising, in combination:

(a) a motor having a stator and a rotor, said-stator including a fieldcoil having two terminals;

(b) a shaft fixedly attached to said rotor;

(c) a first pinion on said shaft:

(d) a switch mounted on said motor, said' switch including' (1) a switchcover formed with two openings,

(2) two resilient conductive means attached to said cover, eachconductive means having two movable end portions,

(3) two push button members slidably guided in respective openings ofsaid switch cover, a pair of respective end portions of said resilientconductive means engaging each of said push buttons and normally holdingthe same in a position in which they outwardly project from said cover;

(4) a pair of fixed contacts aligned with each of said push buttons inthe direction of sliding l movement thereof for contact with respectiveend portions of the associated pair of end portions when said pushbutton is pressed inward of said cover from said position;

(e) two leads respectively connected to one of said resilient conductivemeans and to one of the terrninals of said fieldcoil;

(f) plug means connected to said leads for connecting the same with anelectric cigarette lighter socket in a motor car for energizing saidmotor from a source of current in said car;

(g) first conductor means connecting the other terminal of said fieldcoil to the other one of said resilient conduct-ivemeans;

(h) second conductor means connecting said fixed contacts in circuitwith each other and with said rotor for rotating the same in onedirection when one of said push buttons is pressed while said plug isconnected to said lighter socket, and for rotating said rotor in theother direction when the other push button is pressed;

(i) afirst planet carrier coaxial with said shaft;

(j) a planet gear rotatably mounted on said carrier and meshinglyengaging said first pinion;

(k) a second pinion coaxially fixed on said first planet carrier;

(l) a second planet carrier coaxial with said first carrier;

(m) a planet gear rotatably mounted on said second planet carrier andmeshingly engaging said second pinion;

(11) ring gear means coaxial with said planet carriers and secured tosaid stator against relative rotation, said planet gears meshinglyengaging said ring gear means;

(0) a screw coaxially secured to said second planet carrier;

(p) an elongated hollow internally threaded member threadedly engagingsaid screw;

(q) foot means on said hollow member for supporting the same on asupporting surface;

(r) an outer tube secured to said stator and movably enclosing at leasta portion of said hollow member and of said screw; and

(s) a hook member axially secured on said outer tube.

2. A jack as set forth in claim 1, further comprising pawl means on saidhook member releasably engaging said outer tube for axially securingsaid hook.

3. A jack as set forth in claim 1, wherein said screw is tubular and aportion of said second planet carrier axially extends into said tubularscrew, and key means engaging said screw and said second planet carrierfor preventing relative rotation thereof.

4. A jack as set forth in claim 1, wherein said motor includesstationary brush means movably engaging said rotor for transmittingcurrent thereto, said brush means being connected in circuit with'saidfixed contacts by said second conductor means.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM FELDMAN,Primary Examiner,

1. A MOTOR JACK COMPRISING, IN COMBINATIION: (A) A MOTOR HAVING A STATORAND A ROTOR, SAID STATOR INCLUDING A FIELD COIL HAVING TWO TERMINALS;(B) A SHAFT FIXEDLY ATTACHED TO SAID ROTOR; (C) A FIRST PINION ON SAIDSHAFT: (D) A SWITCH MOUNTED ON SAID MOTOR, SAID SWITCH INCLUDING (1) ASWITCH COVER FORMED WITH TWO OPENINGS, (2) TWO RESILIENT CONDUCTIVEMEANS ATTACHED TO SAID COVER, EACH CONDUCTIVE MEANS HAVING TWO MOVABLEEND PORTIONS, (3) TWO PUSH BUTTON MEMBERS SLIDABLY GUIDED IN RESPECTIVEOPENINGS OF SAID SWITCH COVER, A PAIR OF RESPECTIVE END PORTIONS OF SAIDRESILIENT CONDUCTIVE MEANS ENGAGING EACH OF SAID PUSH BUTTONS ANDNORMALLY HOLDING THE SAME IN A POSITION IN WHICH THEY OUTWARDLY PROJECTFROM SAID COVER; (4) A PAIR OF FIXED CONTACTS ALIGNED WITH EACH OF SAIDPUSH BUTTONS IN THE DIRECTION OF SLIDING MOVEMENT THEREOF FOR CONTACTWITH RESPECTIVE END PORTIONS OF SAID ASSOCIATED PAIR OF END PORTIONSWHEN SAID PUSH BUTTON IS PRESSED INWARD OF SAID COVER FROM SAIDPOSITION; (E) TWO LEADS RESPECTIVELY CONNECTED TO ONE OF SAID RESILIENTCONDUCTIVE MEANS AND TO ONE OF THE TERMINALS OF SAID FIELD COIL; (F)PLUG MEANS CONNECTED TO SAID LEADS FOR CONNECTING THE SAME WITH ANELECTRIC CIGARETTE LIGHTER SOCKET IN A MOTOR CAR FOR ENERGIZING SAIDMOTOR FROM A SOURCE OF CURRENT IN SAID CAR; (G) FIRST CONDUCTOR MEANSCONNECTING THE OTHER TERMINAL OF SAID FIELD COIL TO THE OTHER ONE OFSAID RESILIENT CONDUCTIVE MEANS; (H) SECOND CONDUCTOR MEANS CONNECTINGSAID FIXED CONTACTS IN CIRCUIT WITH EACH OTHER AND WITH SAID ROTOR FORROTATING THE SAME IN ONE DIRECTION WHEN ONE OF SAID PUSH BUTTONS ISPRESSED WHILE SAID PLUG IS CONNECTED TO SAID LIGHTER SOCKET, AND FORROTATING SAID ROTOR IN THE OTHER DIRECTION WHEN THE OTHER PUSH BUTTON ISPRESSED; (I) A FIRST PLANET CARRIER COAXIAL WITH SAID SHAFT